Janner, Tink, and Leeli Igiby thought they were normal children with normal lives and a normal past. But now they know they're really the Lost Jewels of Anniera, heirs to a legendary kingdom across the sea, and suddenly everyone wants to kill them.
In order to survive, the Igibys must flee to the safety of the Ice Prairies, where the lizard-like Fangs of Dang cannot follow. First, however, they have to escape the monsters of Glipwood Forest, the thieving Stranders of the East Bend, and the dreaded Fork Factory.
But even more dangerous is the jealousy and bitterness that threaten to tear them apart, and Janner and his siblings must learn the hard way that the love of a family is more important than anything else.
The Jewels of Anniera, Nia, Podo, and Artham Wingfeather are staying in Artham's treehouse after the events of On the Edge of the Dark Sea of Darkness. They are in no rush to leave, but they know they cannot stay there indefinitely and are debating what to do next. They decide that the best option is to head to the Ice Prairies north, where the Fangs likely will not follow them, as all Fangs fear the cold, and become dysfunctional in cold weather. They prepare to head north.
After Oskar N. Reteep was stabbed, he was found and taken in by a couple in town, one of the few people left in Glipwood. Although his condition is still critical, he is recovering fairly well in a secret room. Unfortunately, the couple taking care of him is arrested by Fangs, leaving no one to care for Oskar. Oskar overhears the Fangs talking, and learns that they know of the Igibys hiding place in the forest and are planning to arrest them soon. Oskar compels himself to take a donkey and ride into the forest to warn the Igibys.
With the Fangs almost literally on his tail, Oskar arrives to find the Igibys in the midst of preparing to go, but Oskar's arrival forces them to cut preparations short and flee. Artham is captured during the flight, and the rest of the party flees to a cliff, sandwitching themselves between a waterfall and the pursuing Fangs. Tink notices a very subtle flight of stairs cut into the face of the cliff. The stairs take them across the waterfall, although there is a gap midway that they have to jump. When they reach the safety of land, Leeli's giant dog Nugget sacrifices himself by breaking the bridge so the pursing Fangs cannot catch them, in the process falling off the bridge to his death.
The party continues northward until they are captured by Stranders, ruthless outlaws who live in this area of the forest. The Strander's leader Claxton intends to kill them, but a combination of Podo's storytelling, Podo and Tink's skill in pickpocketing, and the mercy of the old woman Nurgabog, Claxton's mother who had a crush on Podo in her youth, allows them to live and continue on their journey. Tink even enjoys playing ball with Claxton's daughter Maraly before they go.
Oskar has a friend in the town of Dugtown, who helps them find a guide to take them to the Ice Prairies, but the guide turns out to be a traitor who betrays them to the Fangs. In the confusion, fighting, and fleeing that follows, Janner and Tink are separated from the rest of the family, and they fall asleep in a quiet corner. When they wake up, they attempt to retrace their steps to find their family in a hiding spot where they were supposed to meet, but on the way there, Tink gets angry with Janner and runs off. Janner accidentally takes a wrong turn and gets captured by a group of ragged men and hags, who give him to the Overseer of the Fork! Factory.
The Overseer takes Janner to work at the Fork! Factory. He teaches that Janner is a tool, as are the rest of the children in the factory. Janner's new name is now "tool," and he is generally not permitted to speak, only to nod or shake his head in response to questions. Janner receives a bed and decent food, but work hours are long and hard, and Janner has no rest, even when blisters develop on his hands. Janner attempts to escape, but he is quickly caught and finds himself in shut in a literal coffin for two days and nights as punishment. Janner makes a more careful plan to escape. After stealing fruit and using it to bribe the Overseer's assistant, enlisting the aid of a very brave factory girl, and another three days and nights in the coffin, Janner manages to make a narrow escape and returns to the hideout, hoping his family is still there. He finds old Nurgabog there. Nurgabog says that his family waited for him as long as they dared, but they finally left for the Ice Prairies without him, as they still had Leeli to think of. Nurgabog is also injured from a stab wound in her stomach, coming from her own son Claxton. Nurgabog breaks the news to Janner that Tink, instead of going to the hiding place to find his family, marched right past the hiding place where his family sat waiting for him, without even checking to see if they were there, and went to the Strander camp, demanding to be admitted as a Strander. True to the devious Strander spirit, Claxton locked him up in a cage with other captured children to be delivered to the Fangs. Although Janner had resented Tink for running away, he decides to make rescue trip for Tink.
Janner makes it to the Strander cages by himself, but finds Maraly in one of the cages. Maraly tells him that the Fangs made their rounds a little early this time, and Tink is already gone; Maraly is not in the cage for the Fangs because Claxton is not vile enough to give his own daughter to the Fangs, she is there as punishment because she tried to help Tink escape. Janner frees Maraly from the cage and the head for the Ice Prairies together.
In the bitterly cold mountains, Janner and Maraly meet Gammon, the leader of the resistance in the Ice Prairies. Gammon escorts them to the Ice Prairies, and Janner is reunited with Nia, Podo, Leeli, and Oskar. They deduce that the Fangs took Tink to the Phoob Islands, and decide to rescue him, even though no one has ever been known to escape from the Fangs.
In the meantime, Artham Wingfeather is also at the Phoob Islands. He is locked up in a cage, watching as children are brought in by the Fangs. One by one, the children are taken to a lady, the Stone Keeper, who takes them into a room on top of a dais. There is a song and a flash of light, and the children come out as Grey Fangs. These Grey Fangs are better than the Green Fangs in the rest of the continent of Skree; they are more organized and intelligent, and they can withstand the cold. Artham slips in and out of sanity, being reminded of how he was once in a similar position in the depths of the Castle Throg. Then, he was supposed to sing a song that would change him into a great bird (a hawk, an eagle, or something of the like), but he sang, changed his mind halfway, and stopped singing, resulting in his current bizarre and wild appearance. The Stone Keeper tells him that if he will now sing the song to make his transformation complete, she will release the children. Artham does not really believe her, but his mental agony over leaving his brother Esben years ago finally overcomes him, and he agrees to sing so that he can become forgetful of his anguish and thus be free. At this time, a new load of children comes in, and Artham recognizes Tink among the children. When he tries to change his mind, the Stone Keeper takes Tink into the room on the dais and the song starts. Artham tries to break his cage, and finally sings the song of transformation. Suddenly, he transforms, and his mind becomes clear, as it has not been for a long time. He breaks into the room on the dais and takes furry body in the corner that is Tink, then rushes through a tunnel into the world outside and flies off as the Stone Keeper vainly orders Fangs to pursue them.
Gammon attacks and ties up the Igibys, Oskar, and Maraly to deliver them to the Fangs, saying that he has made a deal with the Fangs to leave Skree if Gammon will give the Fangs the Jewels of Anneira. Gammon regrets the decision, but he values Skree and the Skreean people more than their lives. But when it comes to hand the Igiby party over the the Fangs, Gammon and an army of Skreean people lying in wait launch a surprise attack on the Fangs. Gammon directs the Igibys to a secret route where they can escape to a ship waiting to take them away, providing a guide to help them, but Maraly remains behind, accepting Gammon's offer to her to stay with him. The Igibys and Oskar go down the secret route, but when Podo learns they are going to the sea, the ex-pirate strongly objects. Podo attempts to go back, but the passage is structured in such a way that there is no going back.
The Igiby party boards the ship and set sail, but there going is hampered by attacking Fangs. As the sailors defeat the Fangs, sea dragons rise out of the water. The dragons are angry with Podo and want to kill him, because Podo hunted young sea dragons during his pirate days. Podo knows their anger as well, hence his aversion to being near the sea. At this time, Artham also arrives with Tink. Artham and Janner are the only ones who can understand the sea dragon's speech, because they are both Throne Wardens of Anneira. Artham pleads with the sea dragons to let Podo pass. The dragons are initially vengeful and unwilling to yield, and Podo, recognizing that he is in the wrong, is willing to allow the dragons to take their vengeance on him, but the others, especially Nia, will not let Podo go. One old sea dragon calls up his daughter, a very beautiful sea dragon who was unsuccessfully attacked by Podo and the pirates, and has since become a mangled, hideous wreck. She refuses to attack Podo, however, recognizing that his wounds run deeper than hers. The dragons are reminded of their old alliance with the rulers of Anneira, and Leeli plays "Yurgun's Tune" on her whistleharp, an ancient song that brings comfort to the sea dragons, which they have not heard for a long time. The dragons reach a compromise, where they will allow Podo a final passage across the sea.
Now the ship can sail on, but a new problem has arisen. Everyone is together again, but Tink is now a Grey Fang, with no memory of his family or his name whatsoever. He tries to attack them, and then tries to kill himself by jumping overboard, but Janner jumps in the water after him, becoming severely injured in the process as Tink's claw's scratch deeply into him. Both are rescued and taken below deck to recover. At night, Janner tells Tink stories from Tink's life. Tink continues to snarl, snap, and howl at everyone who approaches him, to the point that Artham even stops coming to see Tink. This continues for many days. One day, Janner tells Tink of Janner's time in the Fork! Factory, and how he tried to rescue Tink, and his desperation when he found out that he was too late to save Tink from the Fangs. At this point, Tink interrupts Janner, saying that he remembers. Janner does not respond, but he hears Tink crying very softly in the dark. The next morning, Nia comes to check on them, and as always, she asks Tink what his name is. Previously, Tink either answered that he does not know or that he has no name, accompanied by a series of growls. This time, Tink answers that his name is Kalmar Wingfeather (Kalmar is Tink's formal name), his father is Esben Wingfeather, and he is the High King of Anneira. He then opens his eyes, and instead of having the wild yellow eyes of a Fang that he previously had, his eyes are now clear and blue.